There are many instances where an obstruction at an outside corner between approximately right angularly arranged surfaces renders the use of a conventional square difficult if not impossible of achievement. The inside corner defined by intersecting inner edges of the arms of the square creates an interference condition with the obstruction at the corner of the right angularly arranged corner surfaces and the angular arrangement of the corner surfaces cannot be precisely determined due to the inability to bring the inner surfaces of the arms of the square into engagement therewith. The conventional square may be positioned in spaced relationship with the corner surfaces and measurements taken to the surfaces in an attempt to ascertain their angular relationship but this is unwieldy and subject to inaccuracies.
It is the general object of the present invention to provide an improved square for use on outside corners having outwardly projecting obstructions at the corners, said square having first and second right angularly arranged arms and an arm interconnecting means which provides a clearance opening for receiving the corner obstruction.
A further object of the invention resides in the provision of an improved square of the type mentioned wherein indicia of measurement are provided along the arms of the square and referenced to an imaginary inside corner whereby accurate measurements may be taken along perpendicular corner surfaces despite the presence of an obstruction at the corner.